Identification_Information: Citation: Citation_Information: Originator: Kasmarek, M.C., Gabrysch, R.K., and Johnson, M.R., 2008 Publication_Date: 2009 Title: Estimated Land-Surface Subsidence in Harris County, Texas, 1915–17 to 2001 Geospatial_Data_Presentation_Form: raster digital data Larger_Work_Citation: Citation_Information: Originator: Kasmarek, M.C., Gabrysch, R.K., and Johnson, M.R., 2008 Publication_Date: 2009 Title: Estimated Land-Surface Subsidence in Harris County, Texas, 1915–17 to 2001 Series_Information: Series_Name: Scientific Investigations Map (SIM) Issue_Identification: xxxx Publication_Information: Publication_Place: Houston, Texas Publisher: U.S. Geological Survey Description: Abstract (SIM 3097) Withdrawal of groundwater has caused compaction of clay layers in the aquifers underlying Harris County, Texas, which in turn has resulted in widespread, substantial land-surface (land) subsidence. The U.S. Geological Survey (USGS), in cooperation with the Harris-Galveston Subsidence District, prepared a map to show the estimated land subsidence that has occurred in Harris County since the early 1900s. The map was constructed using geographic information system (GIS) techniques that involved subtraction of 1915–17 land-surface (topographic map) elevations from 2001 land-surface elevations derived from Light Detection and Ranging (LiDAR) data. Thirty-eight historical (1915–17) 7.5-minute topographic quadrangle maps that together encompass Harris County were used to create a single digital elevation model (DEM) using GIS techniques. A series of 157 LiDAR-based “bare-earth” DEMs from data obtained in 2001 were combined into a single DEM for all of Harris County using GIS techniques. The map (DEM) showing estimated subsidence from 1915–17 to 2001 in Harris County was created by subtracting the 1915–17 DEM from the 2001 DEM using GIS techniques. The subsidence map shows broad agreement with overlain contours of measured subsidence from 1906 to 2000. In the part of the county where the most historical subsidence has occurred, the Baytown-Pasadena area, the map shows subsidence mostly in the ranges from 6 to 10 feet with “patches” of subsidence as much as 14 feet. In much of the central and southern parts of the county, mapped subsidence in the ranges from 3 to 6 feet is most prevalent. The rest of the county, the northwestern and northeastern parts, shows historical subsidence of 0 to 3 feet. The USGS measures cumulative clay compaction continuously at 10 sites in Harris County using 12 borehole extensometers (two at each of two sites). Extensometer installation and the start of groundwater regulation occurred at about the same time (mid-1970s). On average at the extensometer sites, 77 percent of the 1915–17 to 2001 subsidence occurred before regulation (during the first 69 percent of the historical period of record). The average annual rate of subsidence at the sites before regulation was 0.08 foot per year; after regulation, it was 0.05 foot per year. The only site where a greater percentage of total subsidence occurred after regulation, and the annual rate of subsidence between the mid-1970s and 2001 was substantially greater after regulation, was Addicks in the western Houston area, where appreciable groundwater withdrawals continued after the mid-1970s. Purpose: This dataset was created by the USGS Texas Water Science Center, in cooperation with Harris-Galveston Subsidence District (HGSD) to provide resource managers, public officials, researchers, and the general public with ready access to accurate, impartial, scientific information regarding land-surface subsidence in Harris County, Texas, from 1915–17 to 2001. Supplemental_Information: This dataset was developed using a Geographic Information System (GIS). The GIS software used to develop this dataset was Environmental Systems Research Institute's (ESRI, Inc.) ArcDesktop 9.3.1 and ArcInfo Workstation 9.3. References ----------------------- Bowie, W., and Avers, H.G., 1914, Fourth general adjustment of the precise level net in the United States and the resulting standard elevations: U.S. Coast and Geodetic Survey Special Publication No. 18, 328 p. Gabrysch, R.K., and Neighbors, R.J., 2005, Measuring a century of subsidence in the Houston-Galveston region, Texas, USA, in Seventh International Symposium on Land Subsidence, Shanghai, P.R. China, October 23–28, 2005, Proceedings: p. 379–387. Marshall, R.B., 1916, Spirit leveling in Texas 1896 to 1915, inclusive: U.S. Geological Survey Bulletin 637, 254 p. U.S. Army Corps of Engineers, 2009, Corpscon version 6: Topographic Engineering Center, Survey Engineering and Mapping Center of Expertise, accessed June 17, 2009, at http://crunch.tec.army.mil/software/corpscon/corpscon.html U.S. Geological Survey, 2008, Topographic mapping booklet: accessed July 31, 2009, at http://egsc.usgs.gov/isb/pubs/booklets/topo/topo.html Time_Period_of_Content: Time_Period_Information: Range_of_Dates/Times: Beginning_Date: 1915 Ending_Date: 2001 Currentness_Reference: ground condition Status: Progress: Complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -96.010350 East_Bounding_Coordinate: -94.847344 North_Bounding_Coordinate: 30.272086 South_Bounding_Coordinate: 29.352970 Keywords: Theme: Theme_Keyword_Thesaurus: ISO 19115 Topic Category Theme_Keyword: elevation Theme_Keyword: geoscientificInformation Theme_Keyword: imageryBaseMapsEarthCover Theme: Theme_Keyword_Thesaurus: Library of Congress Theme_Keyword: subsidence Theme_Keyword: Light Detecting and Ranging Theme_Keyword: LiDAR Theme_Keyword: hypsometry Place: Place_Keyword_Thesaurus: Geographic Names Information System (GNIS) Place_Keyword: Harris County Place_Keyword: Texas Access_Constraints: None. Use_Constraints: There is no guarantee concerning the accuracy of the data. Users should be aware that changes may have occurred since 2001; therefore some parts of this dataset may no longer be applicable. This dataset should not be used to extract precise subsidence values but instead be used to examine regional patterns of subsidence. The source datasets that were used to develop this dataset were created using different techniques. Users should not use this data for critical applications without a full awareness of its limitations. Acknowledgment of the originating agencies would be appreciated in products derived from these data. Any user who modifies the data is obligated to describe the types of modifications they perform. User specifically agrees not to misrepresent the data, nor to imply that changes made were approved or endorsed by the USGS. Please refer to for the USGS disclaimer. Point_of_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Public Information Officer Contact_Organization: U.S. Geological Survey Contact_Address: Address_Type: mailing and physical address Address: 8027 Exchange Dr City: Austin State_or_Province: TX Postal_Code: 78754 Country: USA Contact_Voice_Telephone: 512-927-3500 Contact_Facsimile_Telephone: 512-927-3590 Contact_Electronic_Mail_Address: gs-w-txpublic-info@usgs.gov Data_Set_Credit: Acknowledgment of the U.S. Geological Survey would be appreciated in products derived from these data. Security_Information: Security_Classification_System: None. Security_Classification: Unclassified Security_Handling_Description: There are no security requirements for handling this dataset. Native_Data_Set_Environment: Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 9.3.1.1850 Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: Subsidence values estimated from this dataset were spot-checked for validity between the two source datasets, by calculating the difference between these two elevation values. They were also compared with a previous study of estimated subsidence for 1906-2001 (Gabrysch and Neighbors, 2005) and showed similar subsidence patterns throughout Harris County. Logical_Consistency_Report: These data were derived by calculating differences in elevation between historical 1915-17 USGS 7.5-minute quadrangles and 2001 LiDAR data. The dataset only contains values from 0 to -20 feet. Completeness_Report: All data represent estimates of subsidence in Harris County, Texas, only for the period from 1915-17 through 2001. Subsidence values ranged from 0 to -20 feet, with areas of no subsidence coded as 0 and a subsidence value of 20 feet coded as -20. Although subsidence values were quantified for the entire county, some areas were coded as "null." Null values (white areas) in this dataset primarily are the result of areas where the land-surface elevation in 2001 was greater than in the 1915-17 period, areas covered by water, or where subsidence was greater than 20 feet. The extreme subsidence and accretion values were likely results of technology discrepancies between periods and anthropogenic influences, such as water-detention structures for flood control, bridge overpasses, and landscape modification in housing developments. There were areas of null values in the upper northeast and northwest sections of Harris County. These areas experienced less development and are located in wooded areas. These values were excluded as the 2001 LiDAR data elevations were greater than the 1915-17 elevations. The differences in these areas were small, from 1 to 2 feet, and could partially be accounted for by reported accuracies of the source data. Additionally, the LiDAR data may not be representative of the bare earth value if the lowest LiDAR return point was attenuated by dense vegetation. Addicks and Barker Reservoirs flood-detention basins visible in the southwest part of the county are null because the fill for the earthen dams was excavated from the basin areas. Lake Houston in the northeastern area of the county is an example of null values as the result of a water body. The many rivers, creeks, canals, and bayous in Harris County are also visible as null values associated with water. Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: For the thirty-eight 1915-17 topographic quadrangle datasets a random sampling of thirty 1-square-mile areas was examined for inconsistent or erroneous elevation contours. The LiDAR data were compiled to meet 3.281-foot horizontal accuracy at the 95 percent confidence level. Quantitative_Horizontal_Positional_Accuracy_Assessment: Horizontal_Positional_Accuracy_Value: 3.281 Horizontal_Positional_Accuracy_Explanation: This is the horizontal accuracy associated with the source data, in feet. Vertical_Positional_Accuracy: Vertical_Positional_Accuracy_Report: The hypsometry from the thirty-eight 1915-17 topographic quadrangle dataset was examined for inconsistent or erroneous elevation contours using a random sampling of thirty 1-square-mile areas. The weighted average of the absolute value of the error for these contours compared to the original quadrangles was 0.01 foot. The elevation accuracy associated with the contours on a quadrangle was plus or minus one-half of the contour interval, or 0.5 foot. The accuracy reported for the 2001 LiDAR data was better than 15 centimeters or 0.5 foot. The accuracy of the subsidence value in this dataset was a combination of the accuracies of the source data. In addition to the reported accuracies, these datasets were collected with widely differing techniques and differing vertical datums. The mean sea level datum for the 1915-17 dataset was the Fourth General Adjustment of 1912. Elevations referenced to this vertical datum were available (Marshall, 1916) to compute a datum change from the Fourth General Adjustment of 1912 to the National Geodetic Vertical Datum of 1929 (NGVD 29). The software, Corpscon version 6, was used to convert the elevations from NGVD 29 to the vertical datum of the LiDAR data, North American Vertical Datum of 1988 (NAVD 88). Quantitative_Vertical_Positional_Accuracy_Assessment: Vertical_Positional_Accuracy_Value: 1.1 Vertical_Positional_Accuracy_Explanation: This is the vertical accuracy associated with the source data, in feet. Lineage: Source_Information: Source_Citation: Citation_Information: Originator: Harris County Flood Control District (HCFCD) Tropical Storm Allison Recovery Project (TSARP) Publication_Date: 2002 Title: 2001 Harris County, Texas LiDAR Publication_Information: Publication_Place: Charleston, SC Publisher: National Oceanic and and Atmospheric Administration, Ocean Service, Coastal Services Center (CSC) Type_of_Source_Media: external hard drive Source_Time_Period_of_Content: Time_Period_Information: Range_of_Dates/Times: Beginning_Date: 20011007 Ending_Date: 20011105 Source_Currentness_Reference: ground condition Source_Citation_Abbreviation: TSARP, 2001 Source_Contribution: 2001 bare earth elevations for creating the 2001 DEM Source_Information: Source_Citation: Citation_Information: Originator: James Freeman Publication_Date: 2005 Title: Contours from Historical USGS Quadrangles in Texas Geospatial_Data_Presentation_Form: vector digital data Publication_Information: Publication_Place: Lakewood, CO Publisher: Digital Data Services, Inc. Other_Citation_Details: 38 historical 7.5-minute USGS quadrangle topographic maps were digitized into GIS line contours having 1-foot contour intervals covering all of Harris County. The topographic maps were derived by using plane table and alidade techniques using ground surveys dated 1915-17. Source_Scale_Denominator: 31,680 Type_of_Source_Media: CD-ROM Source_Time_Period_of_Content: Time_Period_Information: Range_of_Dates/Times: Beginning_Date: 1915 Ending_Date: 1917 Source_Currentness_Reference: ground condition Source_Citation_Abbreviation: Freeman, 2005 Source_Contribution: Digital elevation contours from 1915-17 for Harris County, TX to create the 1915-17 DEM. Source_Information: Source_Citation: Citation_Information: Originator: U.S. Geological Survey Publication_Date: 1915 Title: Topography: Harris County, Texas Geospatial_Data_Presentation_Form: map Publication_Information: Publication_Place: Reston, VA Publisher: U.S. Geological Survey Other_Citation_Details: Quadrangles: Addicks, Aldine, Algoa, Alief, Almeda, Bellaire, Burnett Bay, Cedar Bayou, Clifton by the Sea, Clodine, Crosby, Cypress, Deepwater, Dickinson, Fauna, Genoa, Harmaston, Hillendahl, Hockley, Houston Heights, Huffman, Humble, Katy, La Porte, Louetta, Moonshine Hill, Morgan Point, Mykawa, Park Place, Rose Hill, Satsuma, Seabrook, Settegast, Spring, Stuebner, Swanson, Waller, and Weeden. Source_Scale_Denominator: 31,680 Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Range_of_Dates/Times: Beginning_Date: 1915 Ending_Date: 1917 Source_Currentness_Reference: ground condition Source_Citation_Abbreviation: USGS, 1915 Source_Contribution: Original topographic information from 1915-17. These paper maps were then scanned into digital versions and then georeferenced. Process_Step: Process_Description: (1) Compile the GIS grids of the historical elevation for Harris County. Texas Parks and Wildlife Department supplied (38) individual 7.5-minute quadrangles of 1-foot interval GIS arcs obtained from Digital Data Services, Inc. of Lakewood, Colo. These quadrangles covered all of Harris County and portrayed the land-surface elevation in the 1915-17 time period. These data were created using plane table and alidade techniques (U.S. Geological Survey, 2009). Then, 38 GIS (raster) grids were created from these GIS arc (vector) coverages using the following commands and arguments for the Bellaire quadrangngle as an example: topogrid bellairegd 15;enforce off;datatype contour;iterations 30;contour bellairesp elevation;end. The 38 grids were combined into one DEM dataset called,alltopogridgo, using the ArcInfo Grid command, mosaic. Process_Date: 2006 Process_Step: Process_Description: (2) Compile the GIS grids of the 2001 elevation for Harris County. TSARP supplied 157 individual GIS grids of LiDAR data that were collected after the 2001 Tropical Storm Allison flood in Houston, Texas. The dataset covered all of Harris County, Texas. These grids were combined into one GIS grid dataset or DEM,fullgrid3, using the ArcInfo Grid command, mosaic. Process_Date: 2006 Process_Step: Process_Description: (3) Convert the vertical datum of the historical grid of elevation created in step (1) to NGVD 29. The vertical datum for the 1915-17 DEM was converted from the Fourth General Adjustment of 1912 to NGVD 29. A set of 62 benchmarks were obtained for Harris County and the surrounding area from the National Geodetic Survey (http://www.ngs.noaa.gov/cgi-bin/datasheet.prl, accessed July 9, 2009). Of these, seven were selected to estimate the adjustment from 1912 to NGVD 29. The majority of these benchmarks were not used because these points were located in areas that had experienced historical subsidence. These seven benchmarks were located distal to the estimated 1906-2000 1-foot contour (Gabrysch and Neighbors, 2005). The mean value of the differences between the Fourth General Adjustment of 1912 and NGVD 29 was used to adjust the 1915-17 raster elevations. An adjustment factor of 0.105 foot was calculated and applied to compensate for the difference in vertical datums between the Fourth General Adjustment of 1912 and NGVD 29. The new 1915-17 DEM (with vertical datum of NGVD 29) was named, alltopogridgo: [alltopogridgo] + adjustment factor 1912 to NGVD 29 of -0.105 = [alltopogrid29] Process_Date: 2009 Process_Step: Process_Description: (4) Convert the vertical datum of the (interim historical) grid created in step (3) from NGVD 29 to NAVD 88. The 1915-17 DEM with the vertical datum, NGVD 29 (alltopogridgo), was then converted to the vertical datum, NAVD 88, using the change in elevations obtained from running 100-foot grid cell centers through the Corpscon v. 6 program (http://crunch.tec.army.mil/software/corpscon/corpscon.html, accessed July 13, 2009). The output data derived from the Corpscon program showed that the change in elevation corresponding with the change in vertical datum for Harris County from NGVD 29 to NAVD 88 ranged from -0.04 to 0.18 foot. Prepare input data file of x,y,z values in NGVD 29 for Corpscon program. [alltopo100] = resample([alltopogrid29],100) Generate text file of cell centers of grid, with x,y,z data. alltopo100.txt = sample([alltopo100]) Run the text file through Corpscon. The file, alltopo100.txt, was too large to run through Corpson. The file, alltopo100.txt, was split into five separate files: alltopo.top.txt, alltopo.2.txt, alltopo3.txt, alltopo4.txt, alltopo5.txt. The output files from Corpson were imported a Microsoft Access database to calculate the difference between NAVD 88 and NGVD 29. In ArcMap add these five Microsoft Access tables files and run addxy on these five tables to plot these points temporarily. Using Spatial Analyst, convert features to raster using the difference value and set the environment settings to the same cell size and mask as [alltopo100]. The difference value is the conversion value from NGVD 29 to NAVD 88. The output grids were alltopo_t, alltopo2, alltopo3, alltopo4, alltopo5. Use ArcMap extension, Spatial Analyst command, mosaic,to combine these grids into a single conversion grid from NGVD 29 to NAVD 88, [c29to88_100]. Resample the grid, c29to88_100, which is now at the 100-foot cell size back to the 15-foot subsidence raster cell size. Set cell size and mask equal to [alltopogridgo]. Name the resulting 15-foot resolution grid, c29to88g15. Convert the NGVD 29 elevations to NAVD 88 elevations. [alltopogrid88] = [alltopogrid29] + [c29to88g15] Process_Date: 2009 Process_Step: Process_Description: (5) Create a grid that quantifies the subsidence in Harris County. Subtract the 1915-17 grid from the 2001 grid to produce a new raw (all values that the grid-to-grid subtraction created) difference grid, diffgrid, using the ArcInfo Grid subtraction command: DIFFGRID = fullgrid3 - alltopogrid88. Process_Date: 2009 Process_Step: Process_Description: (6) Modify the subsidence grid to exclude selected conditions. Use grid, diffgrid, to create a new grid,gridwk, that retained only the values between 0 and -20 feet using ArcInfo commands of a conditional statement, con, and the command, setnull. Values greater than zero elevation and values < -20 were set to null using the command: GDWK_NEG20to0 = con(diffgd > 0 or diffgd < -20, setnull(diffgd), diffgd) The grid,diffgrid, initially contained cell elevation values greater than 0 foot and values less than -20 feet. As this project is concerned with subsidence created by subsurface fluid withdrawals, the grid-cell values with elevations greater than 0 foot or less than -20 feet were assumed to be likely caused by other anthropogenic land-surface elevation changes, such as road construction, residential/industrial development, flood-detention ponds, and landfills, and therefore these cells were not representative. Process_Date: 2009 Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: Raster Raster_Object_Information: Raster_Object_Type: Grid Cell Row_Count: 21562 Column_Count: 23940 Vertical_Count: 1 Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Planar: Map_Projection: Map_Projection_Name: Lambert Conformal Conic Lambert_Conformal_Conic: Standard_Parallel: 28.383333 Standard_Parallel: 30.283333 Longitude_of_Central_Meridian: -99.000000 Latitude_of_Projection_Origin: 27.833333 False_Easting: 1968500.000000 False_Northing: 13123333.333333 Planar_Coordinate_Information: Planar_Coordinate_Encoding_Method: row and column Coordinate_Representation: Abscissa_Resolution: 15.000000 Ordinate_Resolution: 15.000000 Planar_Distance_Units: survey feet Geodetic_Model: Horizontal_Datum_Name: North American Datum of 1983 Ellipsoid_Name: Geodetic Reference System 80 Semi-major_Axis: 6378137.000000 Denominator_of_Flattening_Ratio: 298.257222 Distribution_Information: Distributor: Contact_Information: Contact_Organization_Primary: Contact_Organization: U.S. Geological Survey Contact_Position: Ask USGS -- Water Webserver Team Contact_Address: Address_Type: mailing address Address: 455 National Center City: Reston State_or_Province: VA Postal_Code: 20192 Country: USA Contact_Voice_Telephone: 1-888-275-8747 (1-888-ASK-USGS) Contact_Electronic_Mail_Address: http://water.usgs.gov/user_feedback_form.html Resource_Description: Downloadable Data Distribution_Liability: Although these data have been used by the U.S. Geological Survey, U.S. Department of the Interior, no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey in the use of these data, software, or related materials. The use of firm, trade, or brand names in this report is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey. The names mentioned in this document may be trademarks or registered trademarks of their respective trademark owners. Standard_Order_Process: Digital_Form: Digital_Transfer_Information: Format_Name: ARCG File_Decompression_Technique: Winzip Transfer_Size: 1984.351 Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: http://water.usgs.gov/GIS/dsdl/xxxx.zip Fees: None. This dataset is provided by USGS as a public service. Metadata_Reference_Information: Metadata_Date: 20090713 Metadata_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: U.S. Geological Survey Contact_Person: Ask USGS - Water Webserver Team Contact_Address: Address_Type: mailing address Address: 455 National Center City: Reston State_or_Province: VA Postal_Code: 20192 Contact_Voice_Telephone: 1-888-275-8747 (1-888-ASK-USGS) Contact_Electronic_Mail_Address: http://water.usgs.gov/user_feedback_form.html Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata Metadata_Standard_Version: FGDC-STD-001-1998 Metadata_Time_Convention: local time Metadata_Access_Constraints: None. Metadata_Use_Constraints: None. Metadata_Extensions: Online_Linkage: http://www.esri.com/metadata/esriprof80.html Profile_Name: ESRI Metadata Profile